Impregnation, CVD (Chemical Vapor Deposition), etc. are known as method of manufacturing carbon/carbon composite materials. These methods are disclosed, for example, in TANSO SENI SANGYO (CARBON FIBER INDUSTRY) by KENICHI MORITA, KINDAI HENSHUSHA. According to the impregnation method, a prepreg is formed by impregnating a resin material onto a fiber base material. A multi-layered structure of prepregs is molded and cured thereafter. Then, the cured structure is carbonized at a temperature which is finally raised to a high level, thereby forming a carbon/carbon composite material.
As described above, conventional methods such as impregnation, pressure impregnation carbonization, chemical vapor deposition, etc. are often used for manufacturing carbon/carbon composite materials.
These manufacturing methods, however, all have a problem in that a long period of time is required for the manufacturing. More specifically, in the case of the impregnation method, for example, a part of the resin material that impregnates the fiber base material, evaporates in the steps of curing and carbonization, whereby the evaporated material leaves behind open pores. The formation of such pores degrades the density of the material. Therefore, it is necessary to repeat the steps of curing and carbonization a number of times by impregnating with the resin material a number of times, in order to provide a carbon/carbon composite material with a resultant high density. This repeated impregnation results in a complication of the manufacturing process, because it requires a longer time period for manufacturing. The prolonged time period for manufacturing increases the price of end products.
A number of manufacturing methods have been proposed, in which a carbon/carbon composite material can be manufactured in a shorter period of time. These approaches are disclosed, for example, in Japanese Patent Publication No. 63-5349 and Japanese Patent Application No. 61-197467. According to these methods, long fibers are supplied into a matrix material formed by kneading carbon powder and a resin material. An electron deposition body is formed of the long fiber and substances sticking thereto by applying a voltage to the matrix material. After the electron deposition body is cut into sections of prescribed length and molded into bodies of required shaped, the temperature of the molded bodies is raised to a high level, thereby providing a carbon/carbon composite material. According to the just described method, a high performance carbon/carbon composite material can be produced in a short period of time and at lower costs.
However, some fields of technology do not require such a high performance carbon/carbon composite material. A carbon/carbon composite material above mentioned by the proposed method is being therefore perceived as too expensive for use in such fields of the industry where high performance materials are not essential.
It is difficult to manufacture a carbon/carbon composite material having a certain degree of strength (performance) in an economically efficient manner by using the conventional methods of manufacturing a carbon/carbon composite material.